Alternating-current induction motor



Jan. 9, 1923. y 1,441,429.

J. F. KELLY.'

ALTERNATTNG CURRENT INDUCTION MOTOR.

URIGNALFILED'IULYZI,1916.

Patented Jan. 9, 1923.

UNITED STATES PATENT OFFICE.

JOHN F. KELLY,` 0F TROY, NEW YORK, ASSIGNOR TO FEDERAL SIGNAL COMPANY, A CORPORATION OF NEW YORK.

ALTERNATING-CURRENT INDUCTION MOTOR.

Application filed lluly 21, 1916, Serial No. 110,529.

tors, ot which the following a specification.

My invention relates to induction motors, and the object of my invention is to provide an'induction motor of the two element type operating either on two phases or in a single phase split. in any of the well-known ways, and particularly Such motors applied to relays for control of circuits such as are used for signaling purposes; together with such other elements and combinations as are hereinafter more particularly set torthy and claimed.

I accomplish these objects by means of the mechanism illustrated in the accompanying drawings in which:

Fig. 1 is a partial view of an induction type relay and motor illustrating my method of placing and winding the fields.

Fig. 2 is a side view of Fig. l.

Similar numbers refer to similar parts throughout the several views.

The two element type of motor is used tor operating these relays to get a morey eiiicient operating device and to make its control more iiexihle. As an example of this take such a relay used in connection with a track circuit where the two rails ot' the track are used for transmitting the power to one element; on account of'th'eir proximity to the `ground the rails make a very poor transmission line so that the power to be transmitted is kept as low as possible. The other element ot the motor is energized locally and it usually takesthe `greater part ol the power necessary for the operation ot the Telav. By heine; biased either by counters weights or springs`r these relays have a predetermined position to which they return when either element is deenergized. Such a relay could be returned to its biased position by deenergizing either element of the Renewed September 18, 1922. `Serial No. 589,014.

Usually one element of the motor is continuously energized and the relay control is at'- iected by changing the current in the other.

In the construction of such motors, it has heretofore been the practice to arrange the iron in the magnetic circuit and the energizing coils of one element in symmetrical relation to the iron in the magnetic circuit and the energizing coils of the other element, the coils being made up independently for the different poles of the magnetic circuits. This practice being that in use in the manufacture of the .ordinary induction motors of commerce which are designed for continuous running and to have all its elements dc energized to stop its rotation.

It has heen found that when such motors are applied to relays for signaling purposes and where, as stated above, they are controlled by deenergizing one element only, it is possible to have a short circuit on one or more coils of either element in such a way that the power in one element will tend to cause a rotation of the moving parts of the` motor, even though the other elementv is deenergized. Vhen used in connection with signal apparatus this unwarranted motion might give a. false clear and is obviously an unsafe condition and it is the purpose of my invention to overcome this unsafe condition.

My invention consists of arranging the coils of the diiferent elements of the motor so that even though one or more coils break down or are short circuited, a wrongful torque will not be exerted by the energization, of one element only.

Referring to the drawings, 1 represents the energizing coil of the main or locally energized element and 4 represents the iron laminations which lform the magnetic circuit of that element. 2 is the energizing coil of the line or` controlled element and 3 and 5 are the iron laminations which form the magnetic circuit of that element. It will he seen that the coil 2 is made to surrround and energize both of the magnetic circuits 3 and 6 is a disc or rotor of conducting, nonmagnetic material, preferably aluminum or copper, and forms the moving element of the motor.

7 and 9 are wires carrying electric current to and troni the energizing coil of the controlled element; and 1() and ll. are wires carrying current to and from the energizing coil l oi the main ciel/nent. 12, l2 and 111-, 141-, are the pole ita ot the controlled element ,magnetic circuit, and 15?, 1?, are the pole iaces of the local eleniiuit. l5. is a counterweight to bias the disc, 6. 16, is an nini attached to the disc, (i, carrying and insulated from Contact piece, 17, which is inade to close contacts, 18 and 19,`When both elements of the inotor are energized, or contacts, 2 and 21, when the inotor is deenergized, which latter position is the position that the moving parts of the relay are biased to take. 22, is the center about which the disc, 6, counterweight, 15, and arm, 16, re- Volvo.

l will now briefly describe the operation of this relay and point out the application of my invention thereto The circuit ot the niainselenient Winding is as folloi Ys:

From anl external source of alternating current energy through Wire, 10, to coil, 1, to Wire, 11, to the other side of the external source. rlhis current in coil, 1, sets up a magnetic Hm; inthe laminat-ions, 4t. rlhis linx goes through the disc, 6, at the pole faces, 13, 13, setting up local currents in the disc, 6, in the proximity ot pole races. 13, 13.

The circuit oiI the controlled elementl is as follows: i

Frein an external source of alternating Current energy through Wire, 7, to coil, 2, through Wire, 9, to the other side ot the external source. The current in coil, 2, sets up flux in the iron laininations, 3 and 5, which passes through the disc, 6, at pole faces, 12, 12, and 14,-, 14C, setting up local current in the disc, @,in the proximity oit pole faces, 12, 12' and 14,14. On account of the phase difference between the currents in the coils, 1, and the currents set up in the disc, 6, by the :flux in the main or local eleinent reacts on the flux set up in the line or controlled element and conversely t-he currents in the disc, 6, set up by the flux in the line or controlled element are made to react on the flux in the local or main element. This reaction of the cur-rents in the disc, 6, upon the fluxes threading the disc, 6, causes the disc, 6, to rotate, lifting the counterweight, 15, and carrying arm, 1G, with its contacting 'piece` 17. away vtroni contacts, 2O and 21, and bringing contact piece, 17, up against contacts,18 and 19. This latter position ol the iframes Contact arni is called the enei cd posit-ion of the relay.

will be seen that i'l lthe coils are intact when the current is cut oli7 either element there will no longer be a reacting oli currents and fluxes in the disc, G, therefore there will be no torque exerted and the counterweight, 15, Will bring the disc, 6, to its biased position, breakingl contacts, 18 and 1S), bridging contacts,20, and 21. This is the normal operation of the relay.

It will noW readily be seen that it the coil 2 is Inade to surround the magnetic circuits 3 and 5 Which comprise the line or controlled element that a short circuit, lor instance, from Wire, 7, to 9, will have the sanie effect on the ditlerent parts, and 5, or' the niagnetic circuits of the line element so that there Will be no unbalacing ot the flux or currents in the disc, 6, and, therefore, no torque set up in the disc, 6, tending to rotate it.

1t is obvious that the application shown is only typical and inay be enlarged upon or made to cover conditions where the inagnetic circuit ot' the niain element also inight be divided into several parts, or various other coi'nbinations that niight arise.

llhat l cla-iin as my invention and desire to secure by Letters Patent is:

1. In a tivo phase alternating' current induction motor, rotor biased to one posit-ion` a stator comprising a main field core and auxiliary eld cores placed on opposite sides of said niain held core, an energizing coil surrounding said inain held core, and a second energizing coil surrounding said auX- iliary field cores. Y

2. In a two phase alternating current induction motor, a rotor biased to one position,

a stator comprising a main field core and auxiliary field cores placed on opposite sides of said inain iield core, an energizing coil surrounding said main 'field core, and a second energizing coil surrounding said auxiliary field cores in such manner that current passing therethrough Will pass around one oili said auxiliary field cores in counter direction to that in which it passes around the other of said auxiliary held cores.

In testimony whereof l have aiiixed luy signature in presence of two Witnesses.

JOHN KELLY. Witnesses Burman (hunne. 

